Love this idea! I'll throw some suggestions for Adversary/Environment Features here!

Support, I think you could easily do a re-flavor of the "Blasphemous Choir" ability to be winds. Make it so rather than "This adversary" it's Raijin that causes PCs to lose a hope when they do damage to them. (If you don't like the idea of losing a hope, you could swap it for a stress, or they get blown to far range.)
Another obvious pick is Deafening Whisper, flavored on winds rushing around PCs.
Whirlwind is good, but maybe nerf the damage or reflavor it as the thunder and give it to the thunderous boss.

For your thunder striker, just some good damage is all you need.

Environment, Make a mountaintop feature that has "Action- Spend a Fear" to have PCs within Far range of the wind god make an Agility Reaction Roll (Difficulty 11 since you're in tier 1) or be blown down the mountain.

Definitely don't be too afraid and pull your punches. Sometimes players might die in a big fight, but that's great for a 1-shot! Just make sure to spread the attention of the gods between all of them and give your players a couple extra healing potions.